1. Field of the Invention
The present invention relates to a highly versatile apparatus for depositing, removing, modifying, or polishing a material on a workpiece, such as a substrate. More particularly, the present invention is directed to various pad designs and structures for depositing, removing, modifying and/or polishing a material on a suitable substrate.
2. Description of Related Art
There are numerous processing steps in the fabrication of high performance integrated circuits (ICs), packages, magnetic film heads, thin film display units, and the like. One important step is to deposit, remove, or planarize a conductive or insulative material on a workpiece, such as a semiconductor substrate. Deposition of conductive materials such as copper, gold, nickel, rhodium, and their various alloys may be performed, for example, by electrodeposition.
In inlaid metal technology, a workpiece, such as a substrate 10 shown in FIG. 1a, may consist of various topographical features such as channels 14 and vias 12 etched in a suitable dielectric material 16. The surface of the etched dielectric material 16 is generally coated with a suitable adhesion/barrier film layer 18. Over the barrier layer 18, a suitable plating base layer 20, often called a “seed layer”, is deposited. A conductive layer 22 is then applied over the plating base layer to fill, and preferably over-fill, the vias 12 and channels 14 etched in the dielectric material 16 as shown in FIG. 1c. 
The conductive material may be, for example, Cu deposited by way of a chamber-type device 100 (generally shown in FIG. 1b). The chamber device 100 includes a deposition chamber 102, which contains an anode 104 and electrolyte 106. The anode 104 may be attached to the bottom of the chamber 102.
A holder 108 holds the workpiece, such as the substrate 10. For a detailed description of the holder, reference can be made to the assignee's co-pending application Ser. No. 09/472,523, entitled “Work Piece Carrier Head For Plating and Polishing” filed Dec. 27, 1999, the specification of which is incorporated by reference herein as non-essential matter.
For the deposition process, the substrate 10 is typically immersed in the electrolyte 106 with the aid of the holder 108, which also provides a way of electrically contacting the substrate 10. By applying a potential difference between the anode 104 and the substrate 10 (i.e., the cathode), materials may be deposited on or removed from the substrate. For example, when the anode is more positive than the substrate, copper may be deposited on the substrate 10. If the anode is more negative than the substrate, however, copper may be etched or removed from the substrate. To aid electrolyte agitation and enhance mass transfer, the substrate holder 108 may include a rotatable shaft 112 such that the substrate holder 108 and the substrate 10 can be rotated. The substrate 10 is typically spaced apart from the anode 104 at a distance of at least about 10 mm; this distance may, however, be as great as about 300 mm. The surface of the substrate 10 may contain topographic features, such as the vias 12 and channels 14 illustrated in FIG. 1a. After performing material deposition to fill the various features/cavities using electrolyte containing leveling additives, a variation in the thickness of the deposited conductive material 22 inevitably occurs over the surface of the substrate. This variation in thickness is termed “overburden” and is shown in FIG. 1c with reference to portions 22a and 22b. 
After depositing the conductive material 22 on the top surface of the substrate 10, the substrate 10 is typically transferred to a chemical mechanical polishing (CMP) apparatus in order to polish, planarize, or both polish and planarize the same surface. FIG. 2a illustrates one possible version of a conventional CMP apparatus 200 used to polish/planarize the substrate 10 and/or electrically isolate the deposited conductive material within the particular features located thereon. The substrate holder 208, which may be similar to the holder 108 described above, holds and positions the substrate 10 in close proximity to a belt-shaped CMP pad 214. The belt-shaped pad 214 is adapted to rotate in an endless loop fashion about rollers 216. The polishing/planarizing process occurs when the rollers 216 rotate and the pad 214 is moved with a circular motion while making contact with the surface of the substrate 10. A conventional slurry may also be applied to the pad 214 while the substrate 10 is being polished. The substrate surface after polishing is shown in FIG. 2b. 
The conventional method for depositing a conductive material produces large variations in material overburden across the substrate as shown in FIG. 1c. The conventional CMP of this large overburden causes defects on the substrate 10 such as dishing 22c and dielectric erosion 16c also shown in FIG. 2b. It also is responsible for low substrate processing throughput, which is a major source of manufacturing yield loss.